Input TRS:
    1: active(and(tt(),X)) -> mark(X)
    2: active(plus(N,0())) -> mark(N)
    3: active(plus(N,s(M))) -> mark(s(plus(N,M)))
    4: mark(and(X1,X2)) -> active(and(mark(X1),X2))
    5: mark(tt()) -> active(tt())
    6: mark(plus(X1,X2)) -> active(plus(mark(X1),mark(X2)))
    7: mark(0()) -> active(0())
    8: mark(s(X)) -> active(s(mark(X)))
    9: and(mark(X1),X2) -> and(X1,X2)
    10: and(X1,mark(X2)) -> and(X1,X2)
    11: and(active(X1),X2) -> and(X1,X2)
    12: and(X1,active(X2)) -> and(X1,X2)
    13: plus(mark(X1),X2) -> plus(X1,X2)
    14: plus(X1,mark(X2)) -> plus(X1,X2)
    15: plus(active(X1),X2) -> plus(X1,X2)
    16: plus(X1,active(X2)) -> plus(X1,X2)
    17: s(mark(X)) -> s(X)
    18: s(active(X)) -> s(X)
Number of Rules: 18
Direct QWPOS(Sum) ... failed.